1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a sealant filling apparatus for a liquid crystal display device.
2. Discussion of the Related Art
A liquid crystal display device, among ultra-thin flat panel display devices with a display screen having a thickness of several tens of mm, has a low operating voltage and a low power consumption, and thus is portable, thereby being widely applied to various fields, such as notebook computers, monitors, spacecraft, and aircraft.
As shown in FIG. 1, the related art liquid crystal display device includes a lower substrate 1 and an upper substrate 3, which are opposite to each other, and a liquid crystal layer 5 formed between the lower substrate 1 and the upper substrate 3.
Although not shown in the drawings, TFTs and pixel electrodes are formed on the lower substrate 1, and a light shading layer, a color filter layer, and a common electrode are formed on the upper substrate 3.
A sealant 7, for preventing liquid crystal of the liquid crystal layer 5 from leaking and for bonding the lower substrate 1 and the upper substrate 3 to each other, is formed between the lower substrate 1 and the upper substrate 3.
The sealant 7 is deposited on one of the two substrates 1 and 3 by using a printing method or a dispensing method. Because the printing method requires contact between a printing device and the substrate 1 or 3, an orientation film formed on the substrate 1 or 3 may be negatively affected. Accordingly, a dispensing method is typically used to form the sealant today.
In the dispensing method, a syringe, which is filled with the sealant 7, moves over the substrate 1 or 3, and dispenses the sealant 7 on the substrate 1 or 3 in a designated pattern.
When the sealant 7 is deposited on the substrate 1 or 3 and when the sealant 7 contains foam, the sealant 7 breaks down, thereby causing the liquid crystal to leak to the outside and/or decreasing the adhesive strength between the substrates 1 and 3.
Accordingly, a defoamation process for removing the foam from the sealant is performed before the syringe is filled with the sealant 7. That is, the sealant 7 fills the syringe after the defoamation process.
With reference to FIG. 2, a related art process for filling syringes with a defoamed sealant will be described.
FIG. 2 is a schematic sectional view of a related art apparatus for filling syringes with a defoamed sealant.
As shown in FIG. 2, a related art sealant filling apparatus includes a main body 40 and filling rods 46 at the lower portion of the main body 40.
The main body 40 includes an inlet 43 that is connected to a defoaming tank 30 that supplies a sealant from the defoaming tank 30 to the main body 40, a transfer path 44 that transfers the sealant supplied through the inlet 43, and outlets 45 for discharging the transferred sealant to syringes 50 via the filling rods 46.
The main body 40 is generally made of a metal. The transfer path 44 passes through the main body 40 in the horizontal direction, and the outlets 45 pass through the main body 40 in the vertical direction. Accordingly, first bolts 47 are connected to both ends of the transfer path 44 passing through the main body 40 in the horizontal direction, and second bolts 48 are connected to upper ends of the outlets 45 passing through the main body 40 in the vertical direction.
Because the transfer path 44 and the outlets 45 pass through the main body 40 in the horizontal and vertical directions and the first bolts 47 and the second bolts 48 are connected to the main body 40, when the sealant, defoamed by the defoaming container 30, fills the syringes 50 through the inlet 43, the transfer path 44, and the outlets 45, the sealant may remain on the first bolts 47 and the second bolts 48 and solidify.
When the sealant is stuck to the first bolts 47 and the second bolts 48 and is solidified, the solid component of the sealant may be supplied to the syringes 50, thereby causing the syringes 50 to be poorly filled. When the poorly filled syringes 50 deposit the sealant containing the solid component on a substrate, it is impossible to uniformly deposit the sealant on the substrate.